In the related art, a display module has been known that includes a touch panel disposed on a display region of a display element. As the display element, an active matrix liquid crystal display panel has been known that includes a liquid crystal sandwiched between two substrates facing each other and a TFT as a switching element in each display pixel. Such an active matrix liquid crystal display panel is driven by a scanning drive circuit that successively selects a scanning signal line formed in the liquid crystal display panel to turn on each TFT in order only in a predetermined period and a data drive circuit that supplies a display signal voltage to a data signal line corresponding to a scanning signal line selected by the scanning drive circuit to write the display signal voltage to each display pixel.
A touch panel includes a capacitor formed between each of a plurality of first signal lines and each of a plurality of second signal lines. Further, the first signal line is driven to read a linear sum signal based on an electric charge accumulated in each capacitor from the second signal line, and a touch position is detected on the touch panel on the basis of the read linear sum signal.
The scanning drive circuit described above selects each of the scanning signal lines in synchronization with a horizontal synchronization signal. The data drive circuit switches the display signal voltage supplied to the data signal line in synchronization with the horizontal synchronization signal. Thus, noise is generated in synchronization with the horizontal synchronization signal. The noise is then superimposed on a voltage for driving the touch panel, and causes an error in detection of a touch position.
On the contrary, noise is generated due to drive and a read action of the touch panel. The noise is then superimposed on a voltage for driving the display element, appears in a screen displayed by the display element, and has an adverse effect on a display action of the display element.
To solve the problems, PTL 1 discloses the prior art that stops driving a touch panel in a period for driving a display element and drives the touch panel in a period for stopping drive of the display element to drive the display element and the touch panel in a time-division manner.